Field of Invention
The invention relates to a piston for dispensing a flowable component from a cartridge.
Background Information
A piston for dispensing a flowable component from a cartridge is described in WO 2011076663 which has a base body and a venting element. The base body has a component side, an actuation side and a passage connecting the component side and the actuation side and having a passage opening. The venting element has an internal connection element by which the venting element can be connected to the base body and a pin which is partly arranged in the passage opening of the base body. The internal connection element and the pin are connected by a spring element which is in turn connected to the internal connection element along a connection line. The pin of the venting element can adopt a sealing position and an aerating position. In the sealing position, the pin is aligned along an axial direction and closes the passage opening in an airtight manner. In the aerating position, the pin is arranged with respect to the base body such that an exchange of air is possible between the component side and the actuation side via the passage. In this respect, the venting element is arranged and configured such that the spring element urges the pin into the sealing position.
To fill the cartridge, the flowable component is typically filled into the cartridge via an inlet disposed opposite the outlet. Subsequently, the piston is inserted into the cartridge and the cartridge is thus closed in the direction of the inlet. Where possible, no air should be located between the component and the piston since otherwise components of the air can react with the component and can thus negatively influence the quality of the component. The pin of the venting element is therefore brought into the aerating position during or at least at the end of the insertion of the piston into the cartridge so that the air between the component and the piston can escape via the passage and the cartridge is thus vented. To set the aerating position, the pin is urged against the restoring force of the spring element in the direction of the component side and thus an exchange of air is made possible through the passage. After the filling, the pin should remain as securely as possible in the sealing position and thus close the component in an airtight manner in the direction of the inlet of the cartridge.
To dispense the flowable component, the piston is displaced in the axial direction in the direction of the outlet of the cartridge. For this purpose, the piston is acted on by an actuation force by a plunger on the actuation side. Depending on the design of the piston and of the plunger, the pin of the venting element is in this respect brought into the aerating position so that it has to be brought back into the sealing position after the end of the action by the actuation force to achieve an airtight closure of the component.